Capsaicinoid compounds (capsaicin, dihydrocapsaicin etc.), which are a pungent component of chili pepper, are effective for preventing obesity, since these compounds promote energy metabolism, stimulate central nerves to promote hormone secretion and activate lipolytic enzyme. In addition, these compounds sterilize the gastrointestinal tract and improve immunity, and are also effective for activating immunity and relieving fatigue. However, since capsaicinoids irritate mucosa, ingestion in large amounts may upset the gastrointestinal tract. Moreover, individual people do not enjoy the pungent flavor and taste of capsaicinoid compounds.
As less pungent chili pepper, “CH-19 Sweet” (Variety Registration No. 10375), which is a nonpungent fixed variety of chili pepper selected and fixed by Yazawa et al. has been reported to contain a large amount of novel capsinoids (e.g., non-patent document 1). Such compounds belonging to capsinoids (fatty acid ester of vanillyl alcohol, capsiate, dihydrocapsiate etc., hereinafter sometimes to be simply referred to as “capsinoid” or “capsinoids”) are different from capsaicinoid and do not have a pungent taste. However, they have been reported to show an immunity enhancing action, an energy metabolism activation action, oxygen consumption promoting action and the like (e.g., patent documents 1 and 2, and non-patent document 2), and are expected to be starting materials for food and nutritive supplements and related products in the future.
In most chili peppers, vanillylamine is formed from phenylalanine via ferulic acid, vanillin and related compounds, and capsaicinoid is produced from vanillyamine and branched chain fatty acid by capsaicinoid synthase (FIG. 1(a)). In contrast, capsaicinoid is scarcely produced in CH-19 Sweet and capsinoid is produced instead. However, the reason for this has been unknown for years.
As discussed above, capsinoids have a little pungent taste, but yet shows superior physiological activities similar to those of capsaicinoid. Therefore, future application as a starting material for supplements and related products is expected. Therefore, it is desired to clarify the biosynthesis pathway of capsinoids with the aim of breeding and development of new plant varieties capable of producing capsinoids.    patent document 1: JP-A-11-246478    patent document 2: JP-A-2001-026538    non-patent document 1: Yazawa et al., Journal of the Japanese Society for Horticultural Science, vol. 58, pages 601-607, 1989    non-patent document 2: Biosci. Biotech. Biochem., 65 (12), 2735-2740 (2001)